b4 Natural Selection and Genetic Modification

• When bacteria evolve to become able to survive exposure to antibiotics, we say that they have developed:  antibiotic resistance
• Antibiotics only kill bacteria, not viruses. 
• Give 2 reasons antibiotic resistance is becoming more common.
• Give 2 reasons antibiotic resistance is becoming more common.

  doctors often prescribe antibiotics in cases where they aren't necessary. For example, mild or viral infections + Many people don't take the full course of antibiotics, so not all the bacteria are killed
• Why is the spread of antibiotic resistance a problem?

  If more bacteria are resistant to antibiotics, we won't be able to treat those infections This means more people will die of bacterial infections 
• Fossils are the remains of organisms from millions of years ago, which are found in rocks.
• Three main ways fossils can form:

  1. Hard body parts, such as bones and shells, which decay very slowly, are gradually replaced by minerals, forming rock-like substances. Animals can leave impressions or casts, such as footprints or burrows. These become covered by layers of sediment, which eventually become rock.
  2. Some parts of organisms may not decay at all. For example, dead animals and plants can be preserved in amber, peat bogs, tar pits, or in ice.
• The lack of oxygen means that microorganisms can't respire aerobically and so can't carry out the decay process.
• Suggest three ways a species may become extinct.

  Rapid environment change such as an increase in temperature + The spread of a new disease + increased hunting of specie
• The Linnaean classification system was developed by Carl Linnaeus
• What is the correct order of groups in the Linnaean classification system? 

  kingdom, phylum, class, order, family, genus, species. (KPCOFGS)
• What is the term used to describe the breeding together of closely related individuals?

  Inbreeding 
• What are the drawbacks of inbreeding?

  The population as a whole will be more at risk of disease 

  It reduces that size of the gene pool 

  Rare inherited diseases are more likely to appear
• Describe how the process of selective breeding could be used to increase milk production in a population of cows?

  The cows that produce the most milk are selected...

  and bred together

  This process in then repeated with the offspring of those cows

  And again for multiple more generations 
• Two techniques used to clone plants?

  Cutting, tissue culture (micropropagation)
• Cuttings can be used to quickly and cheaply clone a desirable plant
• Process of cuttings - find desirable plant you want to clone, cut of a shoot or a branch than place back in some soil (along with some nutrients) = the cutting will grow into a clone of original plant
• An alternative to using cuttings is to use cell cultures to clone a plant (this is also known as 'micropropagation'). Although it requires more expertise than using cuttings, it can produce many more clone
• Give two benefits of cloning via cuttings rather than micropropagation?

  Cuttings requires less technical expertise and is quicker
• Describe the process of micropropagation to clone plants.

  Cut a small piece of plant tissue, an explant, from the tips of stems, and sterilise them to remove microorganisms. Place the explants in a petri dish that contains agar jelly with growth hormones and nutrients like glucose and mineral ions. Once they grow a bit into calluses, transfer them to soil so they can grow into plantlets. Finally transfer them to their own pot. Ensure that the whole process is done at a reasonable temperature and that the plants get enough light and water.
• What is Genetic engineering?

  The transfer of a piece of DNA from one organism to another organism
• Give three traits that could have been altered by genetic engineering in crops?

  Increased yield e.g. bigger fruit + nutrient count and quality or resistance to disease
• What are the drawbacks of genetic engineering? 

  If the crops breed with wild plants they could spread the new genes and affect the gene pool

  There is a small risk that genetically modified food could negatively affect our health 
• Steps of genetic engineering for human insulin

  1. Isolate the insulin gene from human DNA using restriction enzymes, forming sticky ends.
  2. Use the same restriction enzymes to cut open a bacterial plasmid, forming complementary sticky ends. 
  3. Insert the the insulin gene into the plasmid using the enzyme DNA ligase, to form a recombinant plasmid.
  4. Insert the recombinant plasmid into the host bacteria. 
  5. Let the bacteria divide and then produce the insulin protein. 
• Which two enzymes are used during the process of genetic engineering? 

  • Restriction enzymes 
  • DNA ligase 
• 'Golden Rice' has been genetically modified to produce a chemical that is converted to vitamin A in the body. This is helpful in regions of the world where lack of this vitamin can often cause deficiency diseases, such as blindness
• Give 3 traits that can be improved by genetic modification.

  • increased yield + nutreints and virus resistance